Retort for char kilns



J. C. WAKEFIELD RETORT FOR CHAR KILNS Feb. 27, 1940;.

Filed April 13, 1936 2 Sheets-Sheet 1 Feb. 27, 1940. r J. c. WAKEFIELD 2,191,920

' RETORT FOR CHAR KILNS Filed April 13, 1936 2 Sheets-Sheet 2 five/2501". i i 7 a 4 Patented Feb. 27, 1940 UNITED STATES PATENT OFFICE Application April 13,

2 Claims.

This invention relates to retorts for char kilns, particularly as used in sugar and oil refining, for the renewing and revivifying of filter materials.

As is well known in the art, sugar, petroleum I and a great many other substances, in the course of refining or other processing, are filtered through various filter materials to remove impurities. In a short time, filter materials become so clogged or filled with impurities as to lo lose their filtering properties and so require renewal. In cane sugar refining the filtering material used is bone char, made of ground bone, which is renewed, and its impurities removed, as often as necessary, by exposing it to a very high temperature which burns off the impurities. For this purpose a char house is used having char kilns built therein, with retort tubes for holding the bone char while it is exposed to revivifying temperatures. In the past these retort tubes 20 have been made of cast iron, which were expensive to install and replace, and when one or more burnt out the entire kiln had to be shut down to replace the retorts. They were heavy, requiring a heavy wall casting to supply the necessary 25 strength to withstand the high temperatures, and much of the heat required was wasted in heating the heavy thickness of cast iron.

I have discovered that retorts having the necessary qualities can be made of thin gauge chrlo mium or heat resisting steel, with a great many advantages and savings over the old cast iron construction formerly thought necessary for this purpose, and my invention consists in making these tubes of chromium or heat resisting steels, as a much more satisfactory material for this purpose,

and in the making the retorts of smaller diameter and increasing their number and in providing means therein for thoroughly mixing the char as it passes through the retort, all as described below.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the acccompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or ter- 50 minology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawings:

Fig. 1 is a perspective side elevation of the in- 1936, Serial N0. 74,052

terior of a char kiln, with a battery of retorts in position, to show the construction.

Fig. 2 is a perspective view of a section of a retort.

Fig. 3 is a perspective view of Fig. 1 shown from the top,

Fig. 4 is a vertical section through a retort tube showing bafile means provided therein for thoroughly mixing the char, and

Fig. 5 is a perspective view of the bafile plate.

Referring to the drawings, l0 represents the interior walls of a char kiln, I I the floor, l2 a fire brick wall with a central channel I3 and apertures l4, through which the flames used in heating the bone char are directed. The kiln is enclosed on top by a fiat arch l5 and an inclined roof [6, forming a bin I! for the bone char, and having holes [8 therein connecting with the tops of the retorts, through which the bone char passes during the revivifying process.

The retorts consist of a header 20, a base plate 2| and a plurality of smaller tubes 22 for each header. Tubes 22 are mounted on the header in any suitable manner, as by expanding the tube into the header, riveting or pinning it into the header, or using a bayonet lock. In the drawings, three tubes 22 are shown to each header, but more or less may be used as desired. Previously, a tube 22 has been as large as the header but I find that in reducing the diameter of the tubes and increasing their number, greatly superior results can be obtained in revivification. As

' shown tubes 22 are about three inches in diameter. In a typical installation the header 20 is one to three feet high, and the tubes 22 connected thereto are seven to twelve feet high, and stand vertically so that the char passes through them easily by force of gravity. Valves (not shown) at the bottom of the tubes 22, regulate the speed at which the char is allowed to pass through the tubes. It will be understood that retorts comprising the parts 20, 2| and 22 are repeated in a battery as necessary and Will ordinarily comprise a series in two rows extending the length of the char house or forty retorts in all. In the drawings, Figs, 1 and 3, a section of three retort tubes only in two rows is shown. It will be understood tha the impure char is conveyed mechanically or otherwise to the top of the char kiln as shown at 25 and the bin l! is then filled with the same as needed.

To thoroughly mix the char and subject all of it to uniform and even heat, I suspend a long bafile plate in each tube 22, which hangs vertically therein from the top and has baffles 3| formed out of the plate at frequent intervals which are tilted outwardly alternately on opposite sides of the plate 30, leaving holes 32 through which the char is directed as it passes down through the tube 22. In this way, the char is thoroughly mixed and all the char is subjected to heat, not merely that near the outside. It is understood that any other suitable means for mixing the char can be used, and that I do not limit myself to the particular form of baflie plates shown.

As previously stated, retort parts 20, 2| and 22 have hitherto been made of cast iron, which had many disadvantages but which was the only material regarded as suitable for this purpose. The material used had to be non-corrosive, and to resist oxidation at high temperatures from 400 to 1700 F. I have discovered that these tubes may be made from a lightgauge chromium or heat resisting steel, with many superiorities, and advantages over the old cast iron. A chromium or heat resisting steel which I have found satisfactory is one known as a stainless iron made of 18% chromium and the remainder of iron. The complete formula for a chromium or heat resisting steel which I have found sat isfactory is:

Iron, balance to make 100.

While the foregoing is a typical formula of a satisfactory steel suitable for my purposes, it is to be understood that I do not limit myself to chromium or heat resisting steel made from this precise formula. Steels having a chromium content from 1 to and a nickel content from 1 to or any combination of the two are also satisfactory,

The advantages and savings of my chromium steel retorts are many. The light construction of the steel makes the tubes easier to install, handle and remove. A five-piece chromium steel retort, comprising parts 20, 2| and 3 tubes 22 weighs about 20 pounds as compared with 450 pounds for a one-piece cast iron retort. Being of sheet metal no patterns are required as in casting. Previously if a few of the single tube heavy cast iron retorts burnt out the entire section had to be removed. With the three thin wall tube retorts, replacement due to the failure of one tube or one third of the retort can easily be made while the retorts are in place. A fuel saving of approximately 35% is made by reason of much greater heat transfer of thin wall steel over that of heavy-wall cast iron. This is made possible because a large proportion of the heat formerly was used in heating the cast iron, before the char could be heated; It formerly required as high as 192,000 B. t. u's to revivify pounds of char. The same amount of char can now be revivified and all impurities removed with. e

the expenditure of approximately 50,000 B. t. u's. Since it is now possible for the heat to penetrate to the center of the tube 22, more uniform revivifying results are secured. All the char is purified, not merely that near the sides of the tubes. The use of my chromium steel retort tubes also permits savings in the design of kilns, a

permitting much lighter and more compact construction. With cast iron retort tubes a considerable space had to be allowed to remove these tubes due to their heavy weight. Because of the weight of cast iron retorts a heavier gen- Being impervious to corrosion, I

comprising a header, a plurality of tubes of smaller diameter and a baflle plate suspended in each tube having bailies formed therein tilting upwardly, and alternately on opposite sides of the baiile plate leaving holes in said plate through which the filter material is directed and thoroughly mixed as it passes through.

2. In a char kiln for revivifying filter materials, a retort comprising a plurality of vertically disposed tubes arranged to receive filter material and permit the latter to move therethrough by gravity, a baflle plate extending longitudinally in each of said tubes and having a plurality of openings therethrough, said bafiie plate having a baffle extending upward and outward from the bottom edge of each of said openings, the adjacent bafiles extending in opposite directions from said plate, said tubes providing an area for contact for said filter material per unit length which;

when expressed by a numeral representative'of said area in square inches does not exceed the wall of said tubes being made of material capable of withstanding high temperatures of from 400 F. to 1700 F, g

JOHN c. WAKEFIELD. 

